The invention relates to the type of knitting machine disclosed in U.S. Pat. Nos. 2,705,408 and 2,821,073, both of whose entire disclosures are incorporated herein by reference. The knitting machine in question includes a first pair of cooperating flat needle beds and a second pair of cooperating flat needle beds arranged behind the first. Cam slides are provided with cams for controlling the motions of the needles in the beds. The cam slides travel in a single direction in a closed path of travel around the two pairs of needle beds.
The present invention relates, in particular, to the performance of loop-transfer operations on such a machine. For loop transfer, a loop on a needle (delivering needle) of one needle bed is to be transferred to the corresponding needle (accepting needle) of the cooperating needle bed.
With knitting machines of the particular type in question, it is already known to use cam slides whose cams cause the needles to perform normal-knitting motions. The cam slides are not capable of causing the needles to perform loop-transfer operations. When loop-transfer is desired, the normal-knitting cam slide is removed and replaced by a special loop-transfer cam slide. This in itself is very inconvenient, and makes completely impracticable the knitting of complicated patterns wherein switchovers between normal-knitting and loop-transfer operation are to be performed at high frequency and in complicated sequences.
Furthermore, the special loop-transfer cam slide is so designed as to include a loop-delivery cam arrangement and a loop-acceptance cam arrangement. However, the construction of these cam arrangements is such that, during loop-transfer operation, the cam slide is only capable of causing loops to be transferred from a predetermined one of the beds of the bed pair to the other bed. The cam slide is not capable of causing loops to be transferred in opposite directions during a single trip of the cam slide along one needle bed pair. This, likewise, greatly limits patterning freedom.
Some years ago, it was proposed to modify the cam slide used on a different type of knitting machine to make the cam slide capable of controlling both normal-knitting and also both types of loop-transfer motion (loop-delivery and loop-acceptance). However, the type of knitting machine involved in that proposal incorporates only a single pair of cooperating needle beds, with the cam slide reciprocating along the length of the needle-bed pair. The cam slide proposed for that type of knitting machine is per se not practicable on the type of knitting machine with which the present invention is concerned. Furthermore, that cam slide was not capable of causing loop transfer to occur in both directions during a single trip of the cam slide in a single direction.